Field of the Invention
The present invention relates to an image forming apparatus, a control method therefor, and a storage medium.
Description of the Related Art
As a technique of reducing the power consumption of an information processing apparatus such as an image forming apparatus, there is known a technique of shifting the apparatus to a low power consumption state (power saving state) such as a sleep state when the apparatus has not been used for a predetermined time. When, for example, the user performs a predetermined operation, the information processing apparatus in the sleep state returns from the sleep state to enter a usable state. Such information processing apparatus is generally configured so that the user can designate a condition for shifting to the sleep state to some extent.
In recent years, because of user's rising awareness of energy saving (power saving), stipulation of various energy saving standards, and the like, there has been an increase demand to shift the information processing apparatus to the power saving state more often. However, if the information processing apparatus is often shifted to the power saving state, a user operation for shifting the apparatus from the power saving state to the usable state may be often required, thereby impairing the user convenience. Especially for an apparatus shared by a plurality of users, such as an image forming apparatus, since users who require power saving and users who require convenience may exist together, it is necessary to provide a condition for shifting to the power saving state, which is suitable for a larger number of users.
With respect to the information processing apparatus, when an external device such as a USB (Universal Serial Bus) device is connected, the type of the external device can be taken into consideration as a condition for shifting to the sleep state. An information processing apparatus disclosed in Japanese Patent Laid-Open No. 2009-302831 acquires a class set in a connected USB device, and automatically controls, based on the acquired class, whether or not to shift an image forming apparatus to the power saving state.
Recent image forming apparatuses are known to be compatible with USB over Network (to be referred to as “USBNW” hereinafter, as needed) technology of performing communication between an external information processing apparatus communicable via a network and a USB device connected to an image forming apparatus. Using the USBNW technology makes it possible to control the USB device via the image forming apparatus by a control application installed in the external information processing apparatus.
In the conventional technique disclosed in Japanese Patent Laid-Open No. 2009-302831, however, if the USB device is connected to the image forming apparatus, a power state to which the image forming apparatus shifts is uniformly determined in accordance with the class of the USB device. Therefore, depending on the class of the USB device, the image forming apparatus does not shift to the power saving state as long as the USB device is connected to the image forming apparatus. This may lead to a situation in which it is impossible to achieve power saving of the image forming apparatus connected to the USB device. To the contrary, depending on the class of the USB device, even though the USB device is connected, the image forming apparatus may shift to the power saving state at the time of connection of the USB device and the USB device may often become unusable. In this case, the USB device cannot be sufficiently used using USBNW communication. This impairs the convenience of the user who often uses USBNW communication.